<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
</head>
<body>

<script type="text/javascript">
	/*
		switch(表达式){
			case value1://做全等
				content1:
				break;跳出分支语句

			case value2://做全等
				content1:
				break;跳出分支语句
			...


			default:
				content; //没有表达式相等就会执行该代码
		}

	*/

	// let res = +(prompt('请输入温度'))

	// switch(res){
	// case  0:
	// 	console.log('厚')
	// 	break
	// case 10:
	// 	console.log('薄')
	// 	break
	// case 20:
	// 	console.log('a薄')
	// 	break
	// default:
	// 	console.log('ll')
	// }

	//输入月份
	let mon = +prompt('月份')
	switch(mon){	
   	case  1:
   	case  3:	
   	case  5:	
   	case  7:
   	case  8:
   	case  10:
   	case  12:		
		console.log('31')
		break
	case 2:
		console.log('28')
		break
	default:
		console.log('30')
	}
</script>
</body>
</html>